Hi everyone I'm new so thanks ahead of time and please bear with me. I have a 00 xj with 6" leafs and 4.5 coils and a 1.25" t-case drop. I currently have a noise coming from What sounds like the rear. Now I am getting vibes at highway speeds from what feels like right under me tho. I did the rear diff 2 months ago and drove to Connecticut and daily to work fine. Recently started doing this I have replaced whole front end except front driveshaft CV joints,swaybar, front diff and pitman arm. I did rear u joints and outter wheel bearings and seals about 3-4 months ago. I have my winter 235/75/15s with stock rims just for the time being till I get my new 31s. Is this possibly my front DS, front diff,rear diff or tires. By the way the vibes usually only start at 65 depending on what seems to be roads as well. My front diff pinion seal is leaking. Once in a while I can hear the whine when accelerating in what seems the rear. Usually more when the Jeep is like coasting faster than what I guess my foot is at. I also did the transfer case about 4 months ago. Any help would be great thank you

 

Any help in a direction would somewhat help as I don't want to get into tearing front dif apart with weather we having I'm thinking of changing front outer pinion bearing to see if anything changes but I'm just looking for some thoughts and opinions

 

try pulling off the front driveshaft and seeing if it makes a difference. I dont think it should unless you are running around in 4wd all the time.

 

The stock rear driveshaft is not compatible with a six inch lift. Even at 4.5" lift, the driveshaft needs to be replaced with a 3-joint shaft like what is on the front of the XJ (double cardon).
Up front, the caster should be adjusted to correct the pinion angle after lifting.